Language
Country/Area
No result found
The deadly threat to elms: Why does one fungus destroy millions of trees?
In the past few decades, elms have faced a deadly threat from Dutch Elm Disease (DED), a disease caused by a fungus that attacks the bark of elm trees. Beetle spread. It is reported that the disease originated in Asia but spread unexpectedly to the United States, Europe and New Zealand, causing devastating effects on local elm trees.
Outbreak and spread of Dutch elm disease
Dutch elm disease is caused by several fungi (tiny fungi) belonging to the phylum Ascomycota. There are three main species: Ophiostoma ulmi, Ophiostoma himal-ulmi and Ophiostoma novo-ulmi. These fungi were first discovered in Europe in 1910 and subsequently entered the United States in 1928. The spread of these fungi relies primarily on three bark beetles: the native elm bark beetle, the European elm bark beetle, and the banded elm bark beetle.
The resistance of elm trees
When faced with the attack of Dutch elm disease, some elm trees have shown specific disease resistance. For example, European white elm synthesizes a triterpenoid substance that is repellent to beetles, which makes the beetles reluctant Eat its bark. This so-called "site resistance" allows these trees to effectively avoid infection.
The self-protection mechanism of trees
When an elm tree is infected, it will trigger a self-protective response against the spread of the fungus, blocking the wooden conduits by forming gum and stagnation bodies in its xylem. Although this natural defense plays a certain role, it may still end up due to lack of Water lacks nutrients and dies.
Symptoms of Dutch elm disease
Initial symptoms of infection usually include the upper branches of the tree beginning to wilt and the leaves turning yellow, which appear in the summer months earlier than the normal autumn leaf loss, gradually spreading throughout the tree, and eventually causing root death.
Disease spread in Europe
Dutch elm disease was first noted in 1910 and spread rapidly throughout Europe. From the first market record in 1921 to the disappearance of almost all mature elm trees in 1990, this process has always been heartbreaking.
"The epidemic caused the death of more than 25 million trees in the UK, and the mortality rate of elm trees in France was as high as 97%."
The situation in the United States
In the United States, Dutch elm disease was first reported in 1928 and quickly spread throughout the country. By 1989, it was estimated that more than 75% of the elm trees were dead, and elm trees in some cities, such as Elm City in New England and Washington, D.C., were also severely damaged.
Epidemic in New Zealand
New Zealand was not immune, with several outbreaks detected in the Auckland area in 1989 marking the spread of Dutch elm disease. Although the government had launched a management plan, it still encountered major epidemic challenges in 2013.
Preventive measures and management
There are a variety of prevention and control measures for this disease, including mechanical pruning, chemical spraying, and biological vaccines. Early chemical control methods such as DDT and spraying pesticides achieved certain results, but they also caused potential harm to the environment.
"Although early prevention and control measures were effective, as time went by, the impact on the ecology became increasingly apparent."
Research on disease-resistant tree species
The selection of disease-resistant tree species has also been a continuous effort in Europe and the United States for many years. By crossing different varieties of elm trees, scientists hope to create elm varieties that are more resistant to disease.
The way forward
Despite continued research into disease resistance in elms, Dutch elm disease still cannot be completely eradicated. Every measure taken verifies the power of nature and science, but time is the best witness. In the future, how to formulate more effective management measures will be an urgent topic for ecological conservationists to think about.
